Conventionally, it has been proposed to compare the shapes or sizes of a plurality of image data items read in a series of image reading processes to each other and allocate each of the read image data items to a spine, an index sheet, or a document or determine the image data item of the spine based on the aspect ratios of the image data items (Japanese Patent Application Laid-open No. 2010-224698).
In addition, a technique has been proposed which stores a cover collection file of document data items in association with the positions at which files are displayed in a file image consisting of a set of images of the files in a file storage device such as a cabinet or locker or a set of only appearance images of the files to allow a required document to be selected from the cover collection file (see Japanese Patent Application Laid-open No. 2002-157274).
Also, a technique has been proposed which places a medium on a platen with the spine surface thereof facing the platen, senses an image of the spine, measures the thickness of the medium from the image, and uses the value of the thickness of the medium actually measured from the image as a storage amount (see Japanese Patent Application Laid-open No. 2011-130266).
Besides, a device for sensing the image of a spine (see “Automation of spine image generation in virtual bookshelf”, Takuya Miyagawa and two others, [online], Mar. 16, 2006, Digital Library, [retrieved from the Internet on Apr. 11, 2013] at <http://www.dl.slis.tsukuba.ac.jp/DLjournal/No_30/3-miyagawa/3-miyagawa.html> and software for manually specifying a region in an image and cutting out the image of a spine (see “How to use ‘cover trimming function’ of ScanSwap”, [online], [retrieved from the Internet on Apr. 11, 2013] at <http:www.geocities.jp/payaneco/usr/scanswap/howtotrim.html> and “‘backMaker’ for making spine and front cover from image file”, Kaoru Misaki, the 110-th installment of SimpleStyle, [online], Jun. 26, 2012, lifehacker, [retrieved from the Internet on Apr. 11, 2013] at <http://www.lifehacker.jp/2012/06/120626simplestyle110.html>) have been used.